Universal intervalometer



UNIVERSAL INTERVALOMETER Filed Sept, 20, 1963 2 Sheets-Sheet 2 SUPPLY RESET UNE GROUND SET VOLTAGE DRI DR! RETURN RETURN OUTPUT WINDTNG INVENTORS u n JOHN M. BERGEY STATE RAYMOND J. ANATER JOHN T. ROLAND BY BRUCE G. STEINER HYSTERESIS LOOP Ale gag MIMM l- MAGNETIC CORE ATTORNEY United States Patent Ofiiice 3,306,208 UNIVERSAL INTERVALOMETER John M. Bergey, Rohrerstown, Raymond J. Anater, Akron,

John T. Roland, Manheim, and Bruce G. Steiner, Richland, Pa., assignors to Hamilton Watch Company, Lancaster, Pa, a corporation of Pennsylvania Filed Sept. 20, 1963, Ser. No. 310,296 9 Claims. (Cl. 102-702) This invention relates to a novel electronic intervalometer and more specifically to a novel aircraft weapons system incorporating the intervalometer and particularly suited for multiple rocket firing.

The advent of multiple rocket firing requirements along with complex tactical situations brought forth the first intervalometers. Used in air-to-air weapons systems, the initial intervalometers were relatively simple mechanical or electro-mechanicl stepping switches which responded to the pilots command.

As aircraft speeds increased and weapons became more sophisticated, the armament delivery techniques required updating. Mechanical gadgetry provided part of the an swer but the additional complexity introduced a glaring shortcomingreliability. Pilots returning from firing missions repeatedly complained of the number of malfunctions encountered. The intervalometer was too often the cause.

The present invention provides a novel device for correcting many of the deficiencies inherent in existing intervalometers and particularly provides a device having increased reliability. The system of the present invention is a unique combination of solid state electronic components arranged to give optimum performance while operating in the rigorous aircraft environment. The lack of moving parts within the/intervalometer adds factors of increased reliability without sacrificing the ruggedness required of air-to-air and air-to-ground weapons systems. The unitof the present invention is of relatively light weight and may be packaged in a small volume so as to satisfy the weight and volume load restrictions in present day aircraft. It is readily adapted to existing weapons systems and exhibits substantially increased versatility in providing the pilot with three possible firing modes, namely single, pairs and ripple firing.

It is therefore one object of the present invention to provide a novel intervalometer.

Another object of the present invention is to provide a novel weapons firing system.

Another object of the present invention is to provide an intervalometer and weapons system having only solid state electronic components.

Another object of the present invention is to provide a weapons system having increased versatility and reliability.

Another object of the present invention is to provide an intervalometer and weapons system having reduced size and weight for use in aircraft.

Another object of the present invention is to provide a weapons system having increased firing interval accuracy.

These and further objects and advantages of the invention will be more apparent upon reference to the following specification, claims and appended drawings, wherein FIGURE 1 is a block diagram of the overall weapons system of the present invention.

FIGURE 2 is a detailed circuit diagram of the aircraft cockpit portion or master mode selector of FIG- URE 1.

FIGURE 3 is a detailed circuit diagram of the basic intervalometer portion of the circuit of FIGURE 1.

FIGURE 4a is typical hysteresis loop for the magnetic core devices used in the present invention, and

end silicon controlled rectifier Q 3,306,208 Patented Feb. 28, 1967 FIGURE 4b illustrates the operation of the inter= valometer cores.

Referring to the drawings and particularly to FIGURE 1, the overall weapons system of the present invention, generally indicated at 10, comprises a master mode selector enclosed in the dashed box 12, electrically connected to a basic intervalometer enclosed in the dashed box 14. The master mode selector portion of the weapons system is located in the aircraft cockpit. It is an integral part of the aircraft weapons system and is constructed to fit into existing armament systems with little or no change. The basic intervalometer 14 is located in the non-expendable rocket launcher or pylon normally underslung on the wing of the tactical aircraft. It receives appropriate inputs from the mode selector 12 in pulse form and through magnetic core logic circuitry converts these inputs to useable squib firing signals. Any aircraft requires only one mode selector 12 but may accommodate as many basic intervalometers 14 as required for its mission. However, for the sake of simplicity only a single basic intervalometer is shown and discussed.

As shown in FIGURE 1, the mode selector 12 includes a power supply terminal 16 feeding in interlock relay 18. The terminal 16 may be connected to the plus 28 volt DC. power supply conventionally available in the aircraft. The output of interlock relay 18 is connected to a trigger or pickel switch 20 and to a mode selector 22. Mode selector 22 is coupled by Way of leads 24, 26 and 28 to the three mode pulse generators comprising a single mode generator 30, pairs generator 32 and ripple mode generator 34. These are, in turn, coupled to an intervalometer drive 36 feeding the core switches 38. Interlock relay 18 is also connected by way of lead 40 to the core switches 38 and to the core matrix 42 forming a part of the basic intervalometer 14. The output of the core matrix fires the squibs illustrated at 44.

FIGURE 2 is a detailed circuit diagram of the master mode selector 12. Power supply terminal 16 is coupled to the interlock relay 18 through a master armament switch 46 which is manually operated. Coil 48 of interlock relay 13 as indicated by the dash line in FIGURE 2 actuates a normally open switch S and a normally closed switch S Coil 48 has one side connected to ground and the other side is connected by way of lead 50 to the master armament switch and hence to the power supply terminal16.

Output from the interlock relay is through input resistor R and a Zener diode Z to the pickel switch 20 labeled S Zener diode Z acts as a voltage regulator.

Pickel switch 20 is connected by way of manual switch S to a single pulse mode generator 30 including a silicon controlled rectifier Q This connection is by way of terminal 1 of switch S through resistor R to the gate of SCR Q The anode of Q is connected to ground by way of capacitor C Current limiting resistor R also connects the anode of Q by way of lead 52 to Zener diode Z Ganged with manual switch S are additional switches 8 and S In addition to the off position each section of manual switch S is provided with positions labeled 1, 2 and 3 representing single mode firing, pairs mode firing, and ripple mode firing, respectively. The position of switch S is manually selected by the pilot in accordance with the desired firing mode.

Terminal 2 of switch S is connected to the pairs mode generator 32 which includes in conjunction with Q a sec- Q is similarly provided with an anode capacitor C, while its gate is connected to a Zener diode Z and to a further capacitor C Terminal 3 of switch S connects the pickel switch 20 to a ripple mode generator 34 which includes a unijunction relaxation oscillator generally indicated at 54. Oscillator 54 includes a unijunction transistor Q and an emitter capacitor C a rectifier diode D and a pair of timing resistors R and R which are selected by the position of a manual switch S The outputs of the pulse mode generators are connected by way of lead 56 to the input windings 58 and 60 respectively of a pair of drive cores labelled M and M Cores M and M are also provided with switch windings 62 and 64 and drive windings 66 and 68 labelled DRl and DR2 respectively. The switch windings 62 and 64 are coupled to the base of respective trigistors Q and Q Lead 4% connected to the interlock rel y 18 passes through the drive cores to form a reset/set winding for each of these cores as more fully explained below. A resistor R and inductor L and further resistor R connect the drive coils DR1 and DR2 by way of lead 70 to the power supply through switch S The trigistors Q and Q are connected to ground by a rectifier diode D and are coupled to a cable connector 72 having seven terminals as shown in FIGURE 2. Terminal 74 is a ground terminal for the power supply, terminal 76 is the reset/set terminal for the reset/ set winding passing through drive cores M and M and terminal 78 is the power supply terminal. Terminals 80 and 82 are the drive and return terminals for drive coil DRl, while terminals 84 and 86 are the drive and return terminals respectively for drive coil DR2.

FIGURE 3 is a detailed circuit diagram of the basic intervalometer 14 of FIGURE 1. As shown, connector 72 is coupled to a plurality of counting cores N through N Corresponding cores actuate a plurality of silicon controlled rectifiers labelled Q through Q The output windings of the cores are coupled to the gates of the silicon controlled rectifiers through rectifier diodes D3 through D12. The transfer windings of adjacent cores are connected together by rectifier diodes D13 through D22. Each of the silicon controlled rectifiers couples the power supply to an output connector J which in turn connects to the squibs 44 in FIGURE 4 labelled 1 through 10. The circuit is grounded as indicated at 88.

FIGURE 4a illustrates a typical hysteresis loop for each of the magnetic cores M M and N through N The magnetic cores exhibit two stable states corresponding to the convention I and 0. As indicated in FIGURE 4a the I state is represented by the positive flux density plus B, while the 0 state is represented by the negative flux density minus B. This notation is purely arbitrary but if one state is called 1 the other state is, by convention, called 0. A particular core once set into a remanent state will remain in thin state of magnetization, that is, store the information, until a magnetomotive force H of sufi'icient amplitude and proper polarity to magnetize the core in the opposite direction is applied to the core. The core will then switch to the opposite remanent state and remain there until further energized.

FIGURE 4b illustrates the action of two of the magnetic cores N and N of FIGURE 3. As illustrated, drive winding DRl is connected to the first core N while drive winding DR2 is connected to the second core N Reset winding 90 passes through both cores. The output winding of core N is connected to silicon controlled rectifier Q which when turned on by the core causes the power supply to fire the squib.

DESCRIPTION OF OPERATION The operation of the universal intervalometer of the present invention can be viewed through eight distinct phases. These are weapon loading, power-on, mode selection, firing trigger, pulse generation, drive-switching, core operation, and squib firing.

Weapon loading The first step of operation is for the loadmaster to connect the intervalometer output connector J to the mating connector from the rocket launcher. Since certain loads can contain nineteen rockets, and since there are a maximum of only ten outputs from the output connector J the mating plug to the intervalometer output connector 11 should have parallel squib firing.

It should be noted that no power is available to any of the sections of either the master mode selector 12 or the basic intervalometer 14 at this time. Switch S of the interlock relay (see FIGURE 2) is open as is the mode selector switch S and the pickel switch S In other words, the system is in the completely safe condition during the loading operation. In the event that aircraft power is on during the loading operation, only S of the open switches mentioned above will be closed. This still results in two open switches and therefore no safety compromise.

Power on After completion of the above steps, the next event normally expected is the availability of plus 28 V. DC. aircraft power. This is fed to the system upon the closure by the loadmaster or pilot of the master armament switch 46. The presence of plus 28 V. DC. power results in two events. A reset/set pulse immediately travels through normally closed switch S of interlock relay 18. This pulse, controlled by current limiting resistor R will set a 1 in drive core M and in intervalometer core N and a 0 in drive core M and in intervalometer cores N through N (FIGURE 3). The setting of either a 1 or 0 in the cores is simply determined by the direction of the core winding.

This momentary application of power erases any previous information in the cores and is necessary regardless of eventual mode selection. The reset/set pulse is only momentary because of the second event resulting from power-on operation. This second event is the energizing of the interlock relay 18. Pulling in of the relay causes the opening of switch S thus ending the reset/set pulse. It also closes switch S and supplies power to the voltage regulator zener diode Z the pickel switch 20 and to switch S Power is also supplied to the anode of silicon controlled rectifier Q and to capacitor C and C No power is supplied to the intervalometer 14 or to any other part of the master mode selector 12 at this time.

Mode selection The intervalometer system is now ready for the pilot to select the operational firing mode. This is accomplished by manually setting the rotary switch R located on the pilots console. Clockwise rotation of switch S in FIG- URE 2 will enable the selection of the single, pairs or ripple mode respectively. Switch 8.; placement connects plus 28 V. DC. power to the intervalometer 14 and the core drive circuit comprising resistors R R capacitorC and inductor coil L in FIGURE 2.

Firing trigger The intervalometer system is now capable of accepting the firing trigger or pickel switch actuation from the pilot. Firing occurs when the pilot manually depresses the pickel switch S thereby supplying a firing signal to the desired mode generator as selected by the position of switch This pickel switch is normally located within the pilots control stick. In the case of radar controlled fire control systems, a signal from the fire control system can be substituted for the manual operation performed by the pilot.

Pulse generation The object of closing pickel switch S in series with switch S is to present a drive pulse or drive pulses to the drive cores M and M shown in FIGURE 2. This is achieved by supplying power to the single pulse generator 30 for the single mode, the two pulse generator 32 for the pairs mode, or the dual frequency oscillator 54 for the ripple mode.

S is placed in the pairs mode The single pulse generator is activated when selector switch S is placed on single, that is, turned one step to the 1 position illustrated in FIGURE 2 and the switch S closed by the pickel actuation. Plus 28 V. DC. power is presented through resistor R to resistor R; which provides the gate voltage to trigger the silicon controlled rectifier Q Capacitor C which had been charged to the zener voltage of diode Z with the closure of switch S then discharges through Q and the series resistance offered by the input windings of drive cores M and M After capacitor C is discharged, the series resistance of Q and the drive core windings is small compared to the resistance of resistor R and the voltage at the anode of Q drops to nearly zero. In etfect a pulse has been delivered to the drive core windings at this time.

Releasing the pickel switch removes the gate voltage from Q and the anode circuit causes conduction through 1 to cease. Capacitor C again charges to the zener voltage and the single pulse generator is ready to deliver another pulse when the pickel switch is depressed a second time. The minimum time interval between pulses is determined by the speed in which capacitor C charges to the zener voltage. This time is dependent upon the values of C and R and can easily be designed to be 1 millisecond or less. The time lapse between pickel actuation and the first output is between 4 to 5 microseconds.

The two pulse generator consists of the single pulse generator and a similar pulse generator with a time delay in the gate circuit of a silicon controlled rectifier. The two pulse generator is activated when selector switch (terminal 2) and the pickel switch S is closed, a pulse is delivered to the drive cores as previously described. At the same time, C charges throughR to the zener Z voltage level and C begins to charge through R When the charge on C exceeds the break-down voltage of zener diode Z the gate voltage to Q is established and Q conducts. C discharges through Q thus delivering a second pulse to the drive cores. The objective of supplying two pulses to the drive cores for each pickel actuation has thus been accomplished. The delay'between the two pulses is dependent on the values of R C and Z A nominal value for the delay is milliseconds but this can be changed considerably if desired. The minimum delay between pulses is a function of the switching speeds of the core material.

The dual frequency oscillator 54 is activated when selector switch S is placed on ripple position (terminal 3) and switch S is closed by pickel actuation. Closure of switch S causes two events to occur. First, an immediate pulse is fed to the drive cores from the single pulse generator. Secondly, power is supplied to the unijunction controlled oscillator.

The oscillator operates in the following manner: capacitor C is charged at a' rate determined by resistor R When the emitter of Q reaches a predetermined voltage, unijunction Q conducts sending a pulse to the drive cores. After capacitor C discharges, the unijunction turns off and the process is repeated. The frequency of oscillation is determined by the values of R and C If select switch S is set to connect R to C the oscillator operation is similar to that described above with the exception of the frequency of operation. The values of R and R are selected to provide 10 c.p.s. and 100 c.p.s. pulses to the drive cores respectively.

The single pulse generator provides a pulse as the pickel switch is closed. The first pulse from the dual frequency oscillator will not occur until Q conducts.

A difference would normally exist in the time between pickel actuation and the first pulse from the oscillator 54 and between any other two pulses from the oscillator. This is due to the fact that the capacitor C initially charges from zero while for every pulse thereafter it charges from the valley point of the unijunction Q The voltage divider network of R and R is added to provide an initial charge on C with the closing of the master armament switch. This circuit eliminates the time delay which would normally be present.

Drive switching FIGURE 2 also depicts the drive and switching circuitry required to operate the core matrix. The drive cores M and M were set by the procedures described above. When a pulse arrives at core M by way of winding 58 as described above, an induced pulse from winding 62 arrives at the base of trigistor Q since core M switches from a 1 to 0 state. This pulse causes Q to conduct through diode D2 and completes the return circuit for drive winding DR1 to switch the 1 from magnetic core N to N Drive winding DR1 at 68 also switches drive core M from a 0 to a 1 state. The next pulse that arrives at the drive cores will not affect core M since it is already at the 0 state but will rather switch core M from a 1 to a 0 state. Core M switching causes an induced pulse to arrive at the base of trigistor Q from winding 64 and consequent conduction of Q through diode D2. Drive winding DR2 receives a pulse and magnetic core N will switch from the 1 state back to the 0 state. Simulantously a l is placed by winding DR2 at 66 back in drive core M and the drive switch process is ready to start all over.

The duration of the drive pulse is determined by the circuit components listed as resistor R capacitor C and inductor L Pulse induction between drive cores M and My, cannot occur through the reset/set windings because of the limited number of turns of these windings and the higher energy required for the resetting event. The purpose of the drive cores, then, is to provide proper turn-0n levels for the bases of trigistors Q and Q and to alternately supply pulses to drive windings DR1 and DR2. The trigistors assure that the 1 state is alternately switched from drive core M to drive core M while controlling which winding receives the power pulse from the power supply line 70.

Core operation Magnetic cores exhibit two stable remanent states corresponding to the convention ones (1) and zeros (0). Reference is made to the hysteresis loop for a magnetic core shown in FIGURE 4a. If one state is called a 1, then the other state is, by convention called a 0. A particular core once set into a remanent state, will remain in this state of magnetizationstore the information-until a magnetornotive force of sufiicient amplitude and proper polarity to magnetize the core in the opposite direction is applied to the core. The core will then switch to the opposite remanent state.

The cores are wound as shown in FIGURE 3 and in FIGURE 4b. There are two drive windings, DR1 and DR2, each lacing every other core. According to the previous description, core N has a 1 while all the other matrix cores has a 0. This condition is initially set when the interlock relay 18 pulls in.

When the first pulse arrives through drive winding DR1, core N is switched from a 1 to a 0 as described above. Core N the next core laced by drive winding DR1, cannot switch since it has a 0 set in. Switching of core N induces a pulse in the transfer winding (see FIGURE 4b) and places a 1 in core N The transfer windings each contain a diode which permits unidirectional operation only. Simultaneously a pulse is induced on the output winding shown on FIG- URE 4b. This pulse is presented to the gate of silicon controlled rectifier Q gate causes this silicon controlled rectifier to conduct. This in turn places ample cur-rent through the squib to 7 fire. Conduction through silicon controlled rectifier Q ceases as the squib firing presents an opening to the silicon controlled rectifier-squib circuit.

The next pulse through the drive cores ends up on drive winding DRZ. The identical procedure occurs on core N causing squib #2 to fire. As many squibs will fire as pulses received at the drive cores. The core matrix thus acts as a solid state stepping switch. The number of steps (pulses) is determined by the master mode selectin-one step for single, two steps for pairs, and all ten steps for ripple.

An additional feature is provided by the transfer winding between cores N and N When the last or tenth pulse is received, core N is again placed in the 1. state and the firing cycle repeats from the beginning. This feature is incorporated so that any squib failure will receive an additional firing chance.

It is apparent from the above that the present invention provides a novel intervaloineter of a very versatile and reliable construction making possible three different modes of firing at the election of the pilot. Utilization of solid state circuitry and miniature magnetic cores results in an unusually small and lightweight device. The universal intervalometer consists of two discrete packages joined by the interconnecting cabling. One of the basic intervalometers 14 is located in each rocket launcher or weapon pylon. Up to seven such packages can be installed per aircraft. Only one master mode selector package 12 is placed in each rocket equipped aircraft.

All the micro-components for the intervalometer 14 can be contained within a 2" long x 1 /2" wide x 1" deep rectilinear envelope. This three cubic inch volume comfortably houses thirty solid-state components, ten resistors, a printed board mounting card, a five pin connector, an eleven pin connector, and the drawn-can cover. The weight of this package is seven ounces maximum. Ample room is available for subsequent inclusion of a mounting flange compatible with end-item use and an O-ring or solder seal is provided, as required.

The master mode selector package 12 is contained in a conventional console opening in the aircraft cockpit. This package is approximately 2%" deep. This envelope contains a relay, a mode selector switch, eight semi-conductors, two drive coils, miscellaneous resistors and capacitors (approximately twenty-one), a mounting plate, and interconnecting wiring. The weight of this package is in the neighborhood of thirteen ounces. Weight, always an important consideration in aircraft equipment, is minimized because of the miniature components employed.

The time delay between successive ignition signals is quite accurate. The unijunction controlled oscillator operates over a temperature range of from -60 F. to 165 F. and is able to hold a hundred cycle per second output, with a plus or minus 3 to 4 percent accuracy with minimum temperature compensation. The 100 c.p.s. mode will operate within plus or minus 5 percent accuracy without temperature compensation and the c.p.s. mode operates without temperature compensation within percent accuracy.

Potting of the electronic components plus sealing of the cover can makes the intervalometer insensitive to pressure and humidity. Complex vibration spectra and shock pulses do not seriously affect the intervals-meter because of the lack of mechanical or electromechanical parts. The light weight and small size make it additionally impervious to mechanical environmental variations. The silicon controlled rectifier gates are located close to the trigger source resulting in short lead lengths, thus minimizing radio frequency interference. The power supply lines are isolated by open switches and common intervalometer grounds are preferably used and isolated from the aircraft or chassis ground. The squib grounds and intervalometer grounds are common. The diodes in the transfer loops prevent inadvertent feedback currents from supplying gate pulses to the SCR switches.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States letters Patent is:

1. An intervalometer comprising a magnetic core matrix stepper switch for generating a squib firing signal for each step of said switch, a pair of drive cores for alternately providing stepping impulses to said stepper switch, a trigger switch, and a plurality of pulse generators including a single pulse generator, a pulse pair generator, and a ripple pulse generator, for energizing said drive cores in response to actuation of said trigger switch.

2. An intervalometer according to claim 1 wherein said ripple pulse generator comprises a relaxation oscillator having a unijunction transistor.

3. An intervalometer according to claim 1 including a first drive winding interlacing alternate ones of the cores of said magnetic core stepper switch, a second drive winding interlacing the remainder of the cores of said magnetic core stepper switch, each of said drive cores being interlaced by one of said drive windings, and an input winding interlacing both of said drive cores.

4. An intervalometer comprising a plurality of magnetic cores changeable between two magnetic remanent states, a first drive winding interlacing alternate ones of said cores, a second drive winding interlacing the remainder of said cores, a transfer winding coupling each core with the next adjacent core for causing a change of state in said each core to produce an opposite change of state in said adjacent core, a squib firing signal output terminal for each of said cores, a power supply terminal, a solid state switch device coupling said power supply terminal to each of said output terminals, an output winding coupling each of said cores to its respective solid state switch device whereby said change of state in each said core activates said respective switch device, first and second drive cores interlaced by said first and second drive windings respectively, an input winding interlacing both of said drive cores, means for setting said first drive core in a first magnetic remanent state and said second drive core in a second remanent state, and means for supplying pulses to said input winding to produce corresponding output pulses alternately on said drive windings.

5. An intervalometer comprising a plurality of magnetic cores changeable between two magnetic remanent states, a first drive winding interlacing alternate ones of said cores, a second drive winding interlacing the remainder of said cores, a transfer winding coupling each core with the next adjacent core for causing a change of state in said each core to produce an opposite change of state in said adjacent core, a squib firing signal output terminal for each of said cores, a power supply terminal, a solid state switch device coupling said power supply terminal to each of said output terminals, an output winding cou pling each of said cores to its respective solid state switch device whereby said change of state in each said core activates said respective switch device, first and second drive cores interlaced by said first and second drive windings re spectively, an input winding interlacing both of said drive cores, means for setting said first drive core in a first magnetic remananent state and said second drive core in a second remanent state, and means for supplying pulses to said input winding to produce corresponding output pulses alternately on said drive windings, said pulse supplying means including a pickel switch, single pulse generator means and multiple pulse generator means, and a mode selector switch for selectively coupling either of said pulse generator means between said pickel switch and said drive core input winding.

6. An intervalometer according to claim including first and second trigistors, a switch winding on each of said drive cores coupled to the base of a respective trigistor, means coupling the emitter-base circuit of said first trigister in series with said first drive winding, and means coupling the emitter-base circuit of said second trigistor in series with said second drive winding.

7. A Weapons system comprising a plurality of magnetic cores changeable between two magnetic remanent states, a first drive Winding interlacing alternate ones of said cores, a second drive winding interlacing the remainder of said cores, a transfer winding coupling each core with the next adjacent core for causing a change of state in said each core to produce an opposite change of state in said adjacent core, a squib firing signal output terminal for each of said cores, a power supply terminal, a solid state switch device coupling said power supply terminal to each of said output terminals, an output Winding coupling each of said cores to its respective solid state switch device whereby said change of state in each said core activates said respective switch device, a rocket firing squib coupled to each of said output terminals, first and second drive cores interlaced by said first and second drive windings respectively, an input winding interlacing both of said drive cores, means for setting said first drive core in a first magnetic remanent state and said second drive core in a second remanent state, and means for supplying pulses to said input winding to produce corresponding output pulses alternately on said drive windings, said pulse supplying means comprising a pickel switch, a single pulse generator, a double pulse generator, and an oscillator pulse generator, means coupling the output of each References Cited by the Examiner UNITED STATES PATENTS 2,396,197 3/ 1946 Peterson.

2,542,794 2/ 1951 Brown 102-702 X 2,846,669 8/1958 McMillan et a1. 340-174 2,887,675 5/1959 Lo et a1 340-174 3,010,030 11/1961 Myers 307-88 X 3,049,627 8/ 1962 Higginbotharn.

3,123,002 3/1964 Spool 102-702 3,128,453 4/1964 Busch 340-174 3,191,060 6/1965 Mahoney 307-885 3,202,831 8/1965 Olson 307-88 X 3,204,225 8/1965 Branley et a1. 340-174 3,206,724 9/1965 Stahl 340-174 OTHER REFERENCES General Electric Transistor Manual, Sixth Edition,

copyright 1962, page 194.

SAMUEL FEINBERG, Primary Examiner. BENJAMIN A. BORCHELT, Examiner. W. C. ROCH, Assistant Examiner. 

1. AN INTERVALOMETER COMPRISING A MAGNETIC CORE MATRIX STEPPER SWITCH FOR GENERATING A SQUIB FIRING SIGNAL FOR EACH STEP OF SAID SWITCH, A PAIR OF DRIVE CORES FOR ALTERNATELY PROVIDING STEPPING IMPULSES TO SAID STEPPER SWITCH, A TRIGGER SWITCH, AND A PLURALITY OF PULSE GENERATORS INCLUDING A SINGLE PULSE GENERATOR, A PULSE PAIR GENERATOR, 